Cigarette smoking accounts for 85% of head and neck cancers and 90% of lung cancer cases. Once a smoker has been diagnosed with cancer, immediate smoking cessation is warranted because continued smoking is related to several adverse health outcomes for cancer patients, including: a reduction in treatment efficacy, an increased risk of developing a second primary cancer, and poorer survival. For these reasons, a high proportion of patients will quit smoking after receiving a cancer diagnosis (42-68%). Unfortunately, there is little information regarding the extent to which cancer patients are able to maintain their abstinence. Studies on smoking relapse among cancer patients have been scant and have had important methodological limitations (e.g., measuring rates of relapse in the context of an intervention study, infrequent follow-up). The large number of cancer patients making a quit attempt offers a unique window of opportunity to provide a relapse- prevention intervention; yet, to date, none have been developed. Thus, the current study seeks to acquire the knowledge needed to develop a smoking relapse intervention designed for cancer patients. Testing both empirically-based and theory-based relapse risk factors (e.g., negative affect, motivation), as well as cancer specific risk factors (e.g., fatigue, fear of cancer recurrence), will aid in the development of a targeted smoking relapse intervention. The formative and quantitative findings from this project will be used in a future study to adapt relapse prevention interventions, previously demonstrated efficacious, to address the unique needs and significant smoking relapse risk factors of cancer patients. Specific Aim 1: The overarching aim of this study is to gather data on smoking relapse among lung cancer and head and neck cancer patients, with the ultimate goal of developing a relapse prevention intervention for this population. Specific Aim 2: To identify patient perspectives on predictors of smoking relapse, intervention content, and format, via qualitative research methods. Specific Aim 3: To investigate empirically the precipitating events and predictors of smoking relapse among lung cancer and head and neck cancer patients. Efforts aimed at maintaining tobacco abstinence among this population could have significant public health implications, including improved physical functioning, quality of life, and survival for cancer patients. The overarching aim of this study is to gather data on smoking relapse among lung cancer and head and neck cancer patients, with the ultimate goal of developing a relapse prevention intervention for this population. Efforts aimed at maintaining tobacco abstinence among this population could have significant public health implications, including improved physical functioning, quality of life, and survival for cancer patients. [unreadable] [unreadable] [unreadable]